JPS58117967A - Controller for refrigeration cycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration cycle control device, which detects the state of the refrigeration cycle in a refrigeration system or air conditioner using an electric expansion valve such as a thermoelectric expansion valve, and controls the refrigeration cycle using an electric 11M valve. The purpose is to always maintain high efficiency by controlling the cycle to 1+t% and improving responsiveness to sudden load fluctuations, etc. for optimization.

Traditionally, as a means of optimizing the refrigeration cycle, a method has been adopted to maintain the difference between the evaporator temperature and the compressor suction temperature, or the degree of superheat, at a predetermined value. Conventionally, as this type of control device,
In order to maintain the degree of superheat at a set value, a method has been considered in which the proportional integral or the derivative of the proportional integral is continuously controlled according to the value of the deviation. Although this method has good characteristics under stable control conditions, the change characteristics of the degree of superheat due to changes in the state of the refrigeration cycle may be slow on the order of minutes or fast on the order of seconds. Due to the problem of response speed, it is extremely difficult to configure a control system to constantly maintain the degree of superheat at the set value in response to these situations. Controlling the degree of superheating often results in large vibrations due to various conditions such as changes in the load condition of the refrigeration cycle, and stable control has not yet been realized.

Conventionally, in order to alleviate the above-mentioned problems, the degree of superheating is compared with a set value, detected in two regions, positive and negative, and depending on the sign, the voltage applied to the expansion valve is set at a predetermined time interval or when the sign changes. There was something that added and subtracted numbers. In this method, the control characteristics of the Vi superheat range are basically in an oscillating state, but if the load on the refrigeration cycle is large and the refrigerant tank M is large, the superheat degree can be controlled to be approximately equal to the set value. However, when the refrigeration cycle is under low load, that is, when the refrigerant flow rate is low, control results in large vibrations, making it easy for the compressor to get into a liquid hack state. In order to improve controllability at low loads, if the voltage value to be added or subtracted is made smaller, if load fluctuation occurs and the superheat degree deviates significantly from the set value, the recovery operation will take an extremely long time, which is a problem in terms of responsiveness. It was supposed to have a

Therefore, the present invention eliminates the conventional difficulties as much as possible, improves stability and responsiveness in superheat control, optimizes the refrigeration cycle, and improves the efficiency (so-called ERR and 5%) of refrigeration and air conditioning equipment.
EER).

In particular, the present invention normally changes the voltage applied to the expansion valve in a relatively small voltage range to achieve a stable fl with extremely low vibration.
If the degree of superheat deviates significantly from the set value due to load f@ etc. and this state continues for a certain period of time, perform corrective action with a large fjt pressure range to hasten the recovery to normal stable control. That is.

Hereinafter, the refrigeration cycle control device of the present invention will be explained based on the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of the refrigeration cycle control device (refrigeration cycle control device) based on the present invention, and the figure particularly shows the case where it is used in a cooling device.
) is a compressor, (2) is a condenser, (3) is a blower for the condenser (2), and (4) is a valve opening that is adjusted by an electric signal. Expansion valve (here, thermoelectric expansion valve) (5)
is an evaporator, (6) is a blower for the evaporator (5), (7) is a first temperature sensor provided at the inlet of the evaporator (5), and (8) is a blower for the evaporator (5).
) is a second temperature sensor provided at the suction part of the compressor (1),
(9) is a control circuit that inputs the wet coal signals from the temperature sensors (7) and (8) and outputs an electric signal (DC voltage) to the expansion valve (4). The expansion valve (4) here is a thermoelectric expansion valve of the IIi energized closed type, and when a DC voltage is applied to the expansion valve (4), the refrigerant flow rate is given in accordance with the voltage.

FIG. 2 shows an example of the characteristics of the refrigerant flow #Q with respect to the voltage VT applied to the expansion valve (4). In Figure 2, QL and QH indicate the minimum and maximum range of refrigerant flow tQ when the compressor (1) is operating, and the reason why there are two curves is due to hysteresis characteristics. It's for a reason.

Therefore, in the configuration shown in Fig. 1, the refrigerant is compressed by the compressor (1) in the path of the condenser (2), the expansion valve (4), the evaporator (51), and the suction part of the compressor (1). It circulates and outputs cooling capacity in the evaporator (5).

In the operation of this refrigeration cycle, the most efficient operating state is when the refrigerant evaporates within the Vip generator (5) and becomes dry saturated vapor at its outlet. However, in the actual configuration, there is a temperature drop due to the passage resistance of the refrigerant piping inside the evaporator (5) and from the evaporator (5) to the compressor (11). It is appropriate to operate the refrigerant gas in a slightly superheated region in order to speed up suction and liquid compression in the gas-liquid mixing region (although this is not always the case if an accumulator is provided). Therefore, in order to achieve such an operating state, the difference between the temperatures detected by the temperature sensors (7) and (8) (
This is called overheating Y 8H), but the set value is always 8Hd.
The applied voltage VTe to the expansion valve (4) is controlled so that the voltage VTe becomes equal to (for example, several degrees, although it varies depending on the refrigerant pipe) and the refrigerant flow rate is controlled.

Superheating & SHFi is not a degree of superheating in the strict sense (superheat), as there is a temperature drop due to passage resistance of the refrigerant piping as mentioned above, compared to that in an ideal refrigeration cycle, but here, Temperature sensor (7) shown in Figure 1
) and (8).

Next, the configuration 8 of the control circuit (9) is shown in FIG. In FIG. 3, αG is an area determination unit, αυ is an arithmetic processing unit, and the decoy is a signal output unit, and the entire arithmetic processing unit 011 and part of the area determination unit αG and signal output unit (6) are connected to a microcomputer. (hereinafter referred to as a microcomputer).

In addition to a part of the microcomputer α3, the area determination unit αG includes a resistor α6, a differential amplifier (161, a D/A converter aη, and a comparator).The signal output unit a2 includes a part of the microcomputer 03 and a , a D/A converter, an operational amplifier (2), a resistor (Qυ), and a transistor (2).

In this configuration, the operation of the area determination unit 00 will be explained. The first temperature sensor (7) and the resistor l'I41 generate a voltage Vl corresponding to the temperature TE at the inlet of the temperature generator (5) and a second temperature. A voltage v8 corresponding to the temperature Ts at the inlet of the compressor (1) is input from the sensor (8) and the resistor (to) to the differential amplifier OQ. This differential amplifier f16ittllEVs and V
The difference in le is amplified and outputted, and the output is a value corresponding to the degree of superheating sH='rB-III. Here, if the set value of superheat degree is SHd, then the deviation Δ
ST (is △SR=SH-SHd. Now, as shown in Fig. 4, since the area A of the deviation △8H is made into 4 areas (At, Azr AL A4), the boundary is △8H=-2.5 , 0.+2.5 deg.

Then, using microcontroller 3, △8H=-2.5,0. +
The digital amount of SHd+△SH is input to the D/A converter 09 in three ways at 2.5 degrees, and the output SHR (
= SHd + Δ8H) and the degree of superheating SR using the comparator ae, it is possible to determine the difference between the current overheating Jf 8H and the set value SHd, that is, the range of the deviation Δ8H.

The four regions shown in FIG. 4 are two regions each for positive and negative values centered around the deviation Δ8H=Odeg.

Next, the operation of the arithmetic processing section will be explained. Arithmetic processing unit α
D is an expansion valve (4) that is output by the signal output unit (company) according to the area A of deviation Δ8H divided by the working area determination unit αG.
This determines the value of the voltage VT applied to.

This arithmetic processing unit circle has a region A that changes during stable control (
For example, from M$ to A4), and the same area A
Every time a predetermined period of time To (for example, 2 minutes elapses), the increase/decrease e corresponding to each state, that is, the amount of change for changing the applied voltage vT, is added or subtracted from the value of the applied voltage VT up to that point, and the new value is calculated. The value of the applied voltage vT to be output is determined.The increase/decrease C in this case is as shown in the following table, for example. "Aν" in the table indicates the value when the applied voltage vT was changed last time. The symbol rAp J Fi indicates the region of the state in which the applied voltage VT is changed this time, and in the case of Ay'?AP, the region A changes and y:, and Ay=A, p. is the same area A for a predetermined time T.

This is a case where the period has passed.

When the increase/decrease e in the table is shown in concrete numerical values, for example, it is as follows.

el-50mV, el=25mV, es-75mV
, e4-OmV.

Ps-100mV In this increase/decrease 1e, the sign of the e11Fi deviation is reversed, and the increase/decrease in the applied voltage vT is reversed.

Therefore, we removed the effects of hysteresis and lysis as shown in Figure 2 (
Tame, e! 1 has a value equivalent to hysteresis (for example, 75 mV
Includes J. Further, el and esFi are each selected to have a value corresponding to the magnitude of the absolute value of the deviation.

The above is the case during stable control, or if there is a sudden load change such as when the air volume of the blower (6) shown in Fig. 1 is changed, the deviation area widens to AI or A4 ( In order to recover from the area of = to As or As, 'l' is constantly increased or decreased by 11 ez for a predetermined period of time.
If a corrective action is performed every 2 minutes, it will take a very long time to actually recover.Although it depends on the situation, it may take more than 30 minutes, for example.

Therefore, in order to avoid such a situation, this arithmetic processing unit changes the increase/decrease el to a sufficiently large elI when a certain period of time T (for example, 4 minutes) has elapsed after reaching the area AI or A4. (for example, 200 mV), and addition and subtraction are performed at predetermined time intervals (2 minutes).

Thereafter, when the area reaches As or A8, the operation again shifts to the above-mentioned stability control.

By this operation, when the degree of superheating SH deviates greatly, the increase/decrease el is increased, and the increased @1' allows for early recovery to stable control. Here, this increase/decrease e
The timing to increase l is to do it immediately when the mosquito transforms from At or A8 to AI or A4, e.g.
Instead, it may be possible to add or subtract the increased e lJ and then add or subtract it for a predetermined period of time (every 2 minutes).If this method is used, it will be a stable control operation that will be AI or A4 only for a short period of time. However, this increased el' is too large, and there is a high possibility that a large oscillation state will occur, so a certain amount of time 〒X (4 minutes) is provided.

Note that the constant time TI = TO (2 minutes) can be handled by setting the value of increase/decrease e1 in the table above to 200 mV, and there is no particular need to set the constant time TX. Depending on the object, it may be easy to fall into a oscillating state, so it is better to select an appropriate one based on stability and responsiveness.With the above operation, the arithmetic processing unit (company) will set the applied voltage after changing ff 11 times to be V'ff. , new applied voltage vT
is given as vT=VTF±e (+ is addition, -t[IN).

Next, the signal output unit α2 outputs the digital signal of the new applied voltage vT value given by the arithmetic processing unit to the D/A converter (
1!1, and its output voltage is applied to the expansion valve (4) using an operational amplifier and transistor c12.

The voltage vT applied to the expansion valve (4) is always maintained at the predetermined value until a new addition/subtraction process is performed in the arithmetic processing unit αυ. Having explained the configuration and operation of the control circuit (9) above, let us now explain the deviation Δ in the degree of superheat when the device shown in Figure '11 is operated using this control circuit (9).
An example of the characteristics of SH is shown in FIG.

FIG. 5(i) shows the characteristics under low load conditions with a small refrigerant flow rate and when the air flow rate of the feeder (6) is at its lowest.

In addition, in Fig. 500, the solid line characteristics are under standard conditions and the air volume of the blower (6) is the maximum g, and the broken line characteristics are the characteristics when there is no function to increase the increase/decrease el. The time t=to is the time when the air volume is changed from the maximum. t2 superheat degree setting value 8Hd
= 4 degrees.

As is clear from the figure, the change characteristics of the deviation ΔBH in a stable state are very good for (i), and 0] has an FR movement of about ±1 deg, but even for (I), this is the same level. If it is kept to a minimum, there will be no problem with the refrigeration cycle.
In terms of efficiency, it's almost impossible to get sick.

5th a? In I(ii), time 1=1. There is a load fluctuation at Therefore, it has sufficiently excellent characteristics.

In order to further improve the characteristics shown in FIGS. 5(i) and (11), it may be possible to change the value of increase/decrease e, the predetermined time To, and the constant time '14. In this case, stability and responsiveness may be improved. It is desirable to make a comprehensive judgment and make a selection.

Here, in the above-mentioned arithmetic processing circuit fall, the increase/decrease lid e
6 is added to the amount equivalent to the hysteresis, but as another method, the increase or decrease equivalent to the hysteresis is set to eO, and only when the applied voltage VT is increased or decreased in the opposite direction to the previous time, the predetermined increase or decrease fit e k-eo is added. It may be added.

Next, other embodiments of the area determination section aOt & arithmetic processing section tll will be described. FIG. 6 simplifies the configuration of the region determination section Oa, and defines the region A as two regions in which the deviation Δ8H is positive and negative, that is, AI when ΔSH<O, and A6 when Δ8H≦0. The increase/decrease e for this area AI+A· is, for example, as follows.

el-50mV, e6"loOmV (including 75rnV equivalent to hysteresis), predetermined time TO = 2 minutes, fixed time IIIx; 7 minutes.

However, el is the same area and after Tx elapses, el'=20
Set to 0 mV.

In this case, the fixed time T is set larger than the value shown in Fig. 5, or this prevents the vibration force from increasing by 1 if the operation to increase el is started too quickly. It's for a reason.

This characteristic according to FIG. 6 is I! Compared to the one shown in FIG. 4, it is generally inferior to the one shown in FIG.

The above deviation area is divided into four areas in Figure 544 and two areas in Figure 146, or by dividing it into other numbers and determining the increase/decrease 11e corresponding to each expansion area, similar operations can be performed. It is clear that this can be done.

The refrigeration cycle control device based on the present invention' has been described above with reference to the embodiment shown in the attached drawing [1i1].
The following configurations are possible.

1) 1# sensors (7) and (8) are respectively connected to the evaporator (
Any position from the inlet of the evaporator (5) to the middle part of the evaporator (5)
) from the outlet of the compressor (1) to the inlet of the compressor (1)
The same operation is possible by determining the relationship between the detected temperature of 1 degree at each position and the degree of superheating, and providing that set value.

2) In the control circuit 1d + 9j, the f# design is mainly based on a microcomputer, but it would also be possible to create S using other digital integrated circuits or analog circuits.

3) As the expansion valve (41), the same type of control may be possible even if a so-called thermoelectric expansion valve is used or an electric expansion valve of other configuration is used.Furthermore, as a characteristic of the expansion valve (4), 2
As shown in the figure, we have explained the case where the hysteresis characteristic is present, but it is better if the hysteresis characteristic can be almost ignored or there is no hysteresis.
In this case, there is no need to provide an increase/decrease eO corresponding to hysteresis in the arithmetic processing unit, and the processing is simplified.

4) In the configuration where the region determination unit [α] compares the degree of superheating 8H and the comparison data 8HR, if the comparator (contact or comparison data 5HRC differential is given), malfunctions at the time of region determination can be prevented. In addition, the temperature signals T and Ts detected by the temperature sensors (7) and (8) are converted into digital signals by a direct converter, and the area can be determined from these. However, it is desirable to select a material according to the purpose of use in terms of cost, performance, etc.

5] Although a cooling device is shown in FIG. 1, the present invention can also be applied to a heat pump air-conditioning device or a refrigeration device.

Although the refrigeration cycle control device of the present invention has been described in detail above,
According to the present invention, in order to maintain the degree of superheat at a set value, the deviation of the degree of superheat from the set value is divided into two or more regions, and an electric signal is sent to the expansion valve by a predetermined increase/decrease I depending on the situation. In addition to making detailed changes, when the degree of superheat deviates significantly from the set value due to load fluctuations, it is detected by not recovering from that area to an appropriate area within a certain period of time, and recovers by increasing the predetermined increase/decrease. This speeds up the operation, and can sufficiently improve stability and responsiveness in controlling the degree of superheating. This improves the efficiency of the refrigeration cycle, especially 8B
It is expected that the ER will be improved, and an extremely excellent effect can be achieved in terms of energy saving.

[Brief explanation of drawings]

'lS1 Zusha A block diagram of an embodiment of the refrigeration cycle control device based on the present invention, Fig. 2 shows the characteristics of the expansion valve in Fig. gJ1, Fig. gJ3 shows the block diagram of the control circuit in Fig. 1, and Fig. 4 Vi Explanatory diagram of area divisions detected by the area determination unit, fifth
The figures are operational characteristic diagrams of the embodiment shown in Figures 1 to 4, and Figure 6.
FIG. 7 is an explanatory diagram of another example of area classification by the Zusha area determination unit. (1) is a compressor, (21ti condenser, (4) is an expansion valve,
+5112 evaporator, (7) company's first temperature sensor, (8)
is the second temperature sensor, (9) is the control circuit, <IG is the area determination section, I is the arithmetic processing section, @ is the signal output section, (13 is the microcomputer, Δ8B is the deviation, A is the area, and e is the increase/decrease. amount, 'r(, h predetermined time, TX is a fixed time, vyFi
It is an electrical signal (applied voltage). Patent applicant's agent 'i,, B patent attorney Takashi Shiraki, , :, +,,'611.2;'1/T (V)

Claims (3)

[Claims] (1) An expansion valve whose throttle amount can be adjusted by an electric signal, a temperature sensor installed at the inlet or middle part of the evaporator, and an expansion valve installed at the outlet of the evaporator or the suction part of the compressor.
! and a control circuit that controls an electric signal to the expansion valve so as to maintain a difference between temperatures detected by the first and second temperature sensors at a set value, and the control circuit includes: A region determination unit that divides the detected temperature difference from a set value to a small value (a region determination unit that divides the detected temperature difference into two or more regions, and a predetermined increase/decrease in the value of the electrical signal corresponding to the region obtained by the region determination unit) an arithmetic processing section that adds and subtracts the amount of , and after a certain period of time has elapsed in a predetermined area, increases and decreases to the predetermined increase/decrease; and a signal output section that outputs an electric signal given from the arithmetic processing section to the bladder inflation valve. Equipped with refrigeration cycle control snow making. (2) The area determination unit is configured to divide the deviation into two areas, positive and negative, and the arithmetic processing unit is configured to increase a predetermined increase/decrease in each of the two areas after a certain period of time has elapsed. A refrigeration cycle control electrical manufacturing device according to claim 1. (3) The region determining section is configured to classify the deviation into three or more regions, and the arithmetic processing section is configured to divide the deviation into three or more regions, and the arithmetic processing section selects the region where the absolute value is the largest when the sign of the deviation is positive and negative after a predetermined period of time has elapsed. The refrigeration cycle control device according to claim 1, wherein the refrigeration cycle control device is configured to increase the increase/decrease in the amount of .